'\" t
.\"     Title: SPI_cursor_open
.\"    Author: The PostgreSQL Global Development Group
.\" Generator: DocBook XSL Stylesheets v1.75.2 <http://docbook.sf.net/>
.\"      Date: 2011-12-01
.\"    Manual: PostgreSQL 9.1.2 Documentation
.\"    Source: PostgreSQL 9.1.2
.\"  Language: English
.\"
.TH "SPI_CURSOR_OPEN" "3" "2011-12-01" "PostgreSQL 9.1.2" "PostgreSQL 9.1.2 Documentation"
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.SH "NAME"
SPI_cursor_open \- set up a cursor using a plan created with \fBSPI_prepare\fR
.\" SPI_cursor_open
.SH "SYNOPSIS"
.sp
.nf
Portal SPI_cursor_open(const char * \fIname\fR, SPIPlanPtr \fIplan\fR,
                       Datum * \fIvalues\fR, const char * \fInulls\fR,
                       bool \fIread_only\fR)
.fi
.SH "DESCRIPTION"
.PP

\fBSPI_cursor_open\fR
sets up a cursor (internally, a portal) that will execute a plan prepared by
\fBSPI_prepare\fR\&. The parameters have the same meanings as the corresponding parameters to
\fBSPI_execute_plan\fR\&.
.PP
Using a cursor instead of executing the plan directly has two benefits\&. First, the result rows can be retrieved a few at a time, avoiding memory overrun for queries that return many rows\&. Second, a portal can outlive the current procedure (it can, in fact, live to the end of the current transaction)\&. Returning the portal name to the procedure\*(Aqs caller provides a way of returning a row set as result\&.
.PP
The passed\-in parameter data will be copied into the cursor\*(Aqs portal, so it can be freed while the cursor still exists\&.
.SH "ARGUMENTS"
.PP
const char * \fIname\fR
.RS 4
name for portal, or
NULL
to let the system select a name
.RE
.PP
SPIPlanPtr \fIplan\fR
.RS 4
execution plan (returned by
\fBSPI_prepare\fR)
.RE
.PP
Datum * \fIvalues\fR
.RS 4
An array of actual parameter values\&. Must have same length as the plan\*(Aqs number of arguments\&.
.RE
.PP
const char * \fInulls\fR
.RS 4
An array describing which parameters are null\&. Must have same length as the plan\*(Aqs number of arguments\&.
n
indicates a null value (entry in
\fIvalues\fR
will be ignored); a space indicates a nonnull value (entry in
\fIvalues\fR
is valid)\&.
.sp
If
\fInulls\fR
is
NULL
then
\fBSPI_cursor_open\fR
assumes that no parameters are null\&.
.RE
.PP
bool \fIread_only\fR
.RS 4
true
for read\-only execution
.RE
.SH "RETURN VALUE"
.PP
Pointer to portal containing the cursor\&. Note there is no error return convention; any error will be reported via
\fBelog\fR\&.
